The chat is available for you to easily have contact with the client.
The chat is good for:
Sell yourself a little extra by showing interest and commitment
Show appreciation for the contract offer that you have received!
Ask questions about the job, directions or contract information to the responsible person when you have been hired for an assignment
Inform if the situation changes with regard to any delay, illness etc. (It is important that you also call the client in case of delays etc.)
This will give the client a good first impression. An open and friendly communication pleases and benefits both your future relationship and your success as a gigger!